Preheat the oven to 350 degrees F. Butter three 8-inch baking pans and line them with parchment paper.

Set a heatproof bowl over a small saucepan of simmering water. Add the German chocolate and melt, stirring occasionally. Remove from heat and cool slightly.

Whisk the flour with the cocoa powder, baking soda and salt in a medium size bowl. In a large bowl, beat the butter with the sugar until light and fluffy, about 3 minutes. Add the eggs and egg yolk and beat into the mixture one at a time. Add the vanilla and mix in. Add the buttermilk and the flour mixture in 3 alternating batches, ending with the flour mixture. Fold in the melted chocolate until incorporated.

Pour the batter into the prepared pans. Bake for about 30 minutes or until a toothpick inserted in the center of the cakes come out clean. Place the cakes on a rack and let cool completely. Turn the cakes out of the pans and peel off the parchment paper.

Add the yolks to a small saucepan and beat with a hand mixer until yolks thicken and begin to ribbon, about 2-3 minutes. Add evaporated milk, sugar and vanilla and mix. Add butter and heat on medium heat, stirring constantly, for about 10 minutes or until mixture becomes golden brown and thickens. Remove from heat and add coconut and pecans. Cool to room temperature.

Using a knife or offset spatula, spread one third of the frosting evenly over the top of one cake. Top with the second cake layer and spread one third more of the frosting on top. Top with the final cake and spread the rest of the frosting. Serve at room temperature.